At the present time, a backlash-preventing bearing used for a vehicle transmission such as a roller clutch, over running clutch, etc., can be rotated in only one direction, but not in the opposite direction. The bearing prevents backlash appropriately in a gear assembly wherein the driving shaft gear is fixed to mesh with the passive shaft gear.
However, when the gear on a stationary passive shaft meshes with the driving shaft gear, the probability that the driving gear will mesh with the passive gear to rotate is approximately even to the probality that it will mesh with the passive gear not to rotate.
That is, when the stationary passive gear meshes with the driving gear, the teeth of the passive gear and the teeth of the driving gear will not always mesh exactly. Sometimes each gear is met with the free ends of teeth so that the power cannot be transmitted from the driving gear to the passive gear.
The above problem occurs because there is no relative clearance for movement between the driving gear and the passive gear. Whether or not the teeth of the gears mesh depends on the conditions of the mating of the teeth.
Therefore, in the backlash-preventing apparatus of the prior art constructed as above, it is difficult for the gear teeth exactly mesh with each other when the passive gear stops. When the high speed rotation of the driving gear, and the severe friction between the backlash-preventing gears and driving gear generate serious noise, prior art apparatus cannot be used for a super high speed rotating apparatus.